Process for removing nicotine from tobacco



United States Patent No Drawing.

9 Claims. (Cl. 131140) This invention relates to the de-nicotinization of tobacco.

The intrinsic flavor of tobacco, as regards both aroma and taste, is adversely affected when the tobacco is exposed -to the action of acids or substances with decidedly acid characteristics in the presence of Water or substantial amounts of water vapor. For this reason, most denicotinization processes scrupulously avoid the use of acids, this notwithstanding the fact that nicotine itself is an alkaloid lending itself to interact-ion with them. On the whole, those skilled in the art consider it wiser to approach in some other way the problem of displacing the nicotine from the tobacco. An example is by treatment of the tobacco with gaseous ammonia, which has been found to be capable of displacing the nicotine suffrciently to permit of its removal by such familiar techniques as solvent extraction.

The present invention, the object of which is to reduce the nicotine content of tobacco to a relatively low level without interfering with the intrinsic flavor of the tobacco, goes counter to the beliefs and recommendations of many skilled in the art. Contrary to their teachings, it contemplates removing the nicotine as a derivative formed by reacting the nicotine with one of the more aggressive acids, specifically hydrochloric acid. 'In practice, however, the latter is not employed in the form of muriatic acid, commercial or otherwise, but in the form of dry hydrogen chloride. Using dry hydrogen chloride it becomes practicable for the first time to form nicotine hydrochloride in situ, thereby facilitating separation of the nicotine from the tobacco. The tobacco is not appreciably affected as to aroma or taste, notwithstanding exposure to the acid.

Other objects, advantages and features of the invention will be apparent from the description which follows, which discloses the invention in what is considered to be its preferred form.

In the practice of the invention, one may use almost any kind of bulk tobacco, regardless of the physical form in which it has been left by prior handling. Preferably, in order to make it easier to reach the nicotine, the tobacco should be in leaf for-m, shredded form or powder form. Whether the tobacco has or has not been subjected to prior curing, as by smoking, is not important. It is, however, of considerable importance that the tobacco should be dry to the touch before it is subjected to the several processing steps involved in the present invention. If it is not, a preliminary drying step is indicated.

Assuming that the tobacco is dry to the touch, in satisfactory condition as regards physical form and spread out on a screen, rack, tray or the like, one may proceed to subject it at ordinary temperatures (50 to 90 F.) to a current of substantially anhydrous hydrogen chloride, either as such or admixed with air. In general, it is best to use commercial hydrogen chloride as supplied in pressure bottles to industrial users, in which form it has a minimum purity of about 99%. When first released from the container, the hydrogen chloride usually becomes admixed With air, which does no harm. On the other hand, an enclosed area with suitable provision for venting tends after a short time to develop an environrnent that consists largely of hydrogen chloride as such.

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With or without admixed air, the hydrogen chloride is best directed to, onto and through the tobacco so as to enable it to react with the nicotine.

As a general rule, not more than ten minutes exposure of the tobacco is likely to be needed, except, perhaps, in unusual circumstances. If, however, the tobacco is well distributed and the hydrogen chloride is not admixed with excessive amounts of air, a period as short as two minutes may suffice. With substantially pure hydrogen chloride, at treatment taking three to five minutes time is all that is normally required. There is no advantage to be gained by using unduly large quantities of hydrogen chloride. In the ordinary sense of the term, the time period is not critical.

Following the treatment with hydrogen chloride, the tobacco should be thoroughly aerated, using a current of dry air for this purpose. The purpose of aerating is to remove any hydrogen chloride adsorbed on the surfaces of the tobacco; in other words, the air acts as a scavenger. Any other inert gas might be used instead, if desired. Whatever the gas, it should be dry or substantially dry. A gas saturated with water vapor would be of very little value because of the tendency of moist tobacco to deteriorate in the presence of hydrochloric acid.

The period of aeration should last long enough to accomplish the intended purpose. As a rule, five to fifteen minutes time is sufiicient, particularly if the air is atmospheric air. As in the case of the treatment with hydrogen chloride, the step of aerating can to advantage be carried out at ordinary temperatures; i.e., temperatures between about 50 and F. However, if desired, the air used in the aeration step may be heated to moderate superatniospheric temperatures; e. g., to F.

After aeration for a period of time which in a typical case may be about ten minutes, the tobacco is subjected to the action of a current of steam. Preferably it is atmospheric steam; that is to say, steam at atmospheric pressure. Saturated steam, including most types of waste steam, is adequate for the purpose; however, dry steam may be used. The purpose of this steam treating operation is to vaporize the nicotine hydrochloride by steam distillation: in typical instances, up to about 90% of the nicotine content of the tobacco may be removed in this manner. The nicotaine hydrochloride may, if desired, be recovered from the condensate. It lends itself to a variety of uses, as in agricultural sprays.

As a rule, the steam distillation step requires about five minutes time. It may, however, be allowed to continue for ten or even fifteen minutes. Although in general the time period is not critical, unlimited treatment with steam would be bad in the sense that it would tend to break down the tobacco itself. There is no point, therefore, to continuing the step beyond the five or ten minutes time required to extract the nicotine hydrochloride from the tobacco.

Thereafter, the tobacco should be dried a second time, as by a current of atmospheric air or other inert gas. This treatment should continue as long as necessary, but as a rule ten to fifteen minutes time will be found to be sufiicient. At this stage, inasmuch as all or substantially all hydrogen chloride has already been removed from the tobacco, there is no particular objection to the presence of water vapor in the air. It is evident, however, that more eflicient operation is likely to be obtained if the air or other inert gas is dry or nearly dry. As a general rule, not over about fifteen minutes time is likely to be needed in order to dry the tobacco.

In practising the process as described above, one should be satisfied that additives such as glycerine, other glycols, sorbitol and the like are absent from the tobacco. Hydrogen chloride has a tendency to react preferentially with such additives. If this is allowed to happen, the purposes of the invention are not served in the sense that the smoking qualities of the tobacco are likely to be impaired. Also, because of the use of hydrogen chloride, the materials of construction should be of such a nature as to resist corrosion: thus stainless steel, hard rubber or the like should be used. In selecting the materials to be employed, consideration should be given to the possible effect on the aroma and taste of the tobacco. Those materials mentioned present no particular problem.

It will be apparent to those skilled in the art that variations in the processes as described above are entirely possible, particularly in respect of temperatures, times and concentrations. From the standpoint of economics, the use of air, steam and hydrogen chloride leaves little to be desired; indeed, the economics of the process are very likely to be unfavorably affected by the substitution of other substances. Nevertheless, such substitutions are possible. In respect of the form of the tobacco, wide variations are permissible: thus in addition to the several forms previously mentioned it may take the form of waste tobacco, stems, etc.

It is intended that the patent shall cover, by summarization in appended claims, all features of patentable novelty residing in the invention.

What is claimed is:

1. A process for reducing the nicotine content of dry tobacco in bulk form comprising the steps of forcing therethrough, in the order stated, a current of a dry gas consisting essentially of anhydrous hydrogen chloride with admixed air, a scavenging current of an inert gas, and a current of steam, such steps being performed sequentially.

2. A process according to claim 1 wherein air is used as the scavenging gas.

3. A process according to claim 1 wherein the steam is atmospheric steam.

4. A process for reducing the nicotine content of dry tobacco in bulk form comprising the steps of converting the nicotine to nicotine hydrochloride by exposing it to the action of substantially anhydrous hydrogen chloride; thereafter. blowing air through the tobacco for a period of time sufiicient to eliminate residual hydrogen chloride remaining unreacted in the tobacco; thereafter removing the nicotine hydrochloride'from the tobacco by steam distillation; and thereafter drying the tobacco.

5. A. process according to claim 4 wherein. the distillation step makes use of saturated steam.

6. A process according to claim 5 wherein the steam is at atmospheric pressure.

7. A process for reducing the nicotine content of dry tobacco in bulk form comprising the steps of converting the nicotine to nicotine hydrochloride by exposing it for a period of about five minutes to the action of substantially anhydrous hydrogen chloride; thereafter biowing air through the tobacco for a period of time sufficient to eliminate residual hydrogen chloride remaining unreacted in the tobacco; thereafter removing the nicotine hydrochloride from the tobacco by steam distillation; and thereafter drying the tobacco.

8. A process for reducing the" nicotine content of dry tobacco in bulkform comp-risingthe steps of converting the nicotine to nicotine hydrochloride by exposing it to the action of substantially anhydrous hydrogen chloride gas; thereafter blowing air through the tobacco for a period of time sufficient to eliminate residual hydrogen chloride remaining unreacted in the tobacco; thereafter removing the nicotine hydrochloride from the tobacco by steam distillation for a period of about five minutes; and thereafter drying the tobacco.

9. A process for reducing the nicotine content of dry tobacco inbulk form comprising the steps of converting the nicotine to nicotine hydrochloride by exposing it for a period of about five minutes to the action of substantially anhydrous hydrogen chloride; thereafter blowing air through the tobacco for a period of time sufiicient to eliminate residual hydrogen chloride remaining unreacted in the tobacco; thereafter removing the nicotine hydrochloride from the tobacco by steam distillation for a; period'of about five minutes; and thereafter drying the tobacco.

References Cited in the file of this patent UNITED STATES PATENTS 259,553 Kissling June 13, 1882 2,136,485 Berka et a1 Nov. 15, 1938 2,429,567 Sowa Oct. 21, 1947 2,985,549 Rosenthal May 23, 1961 FOREIGN PATENTS 10,381 Great Britain 1904 OTHER REFERENCES Organic Chemistry, by F. S. Kipping and F. B. Kipping, Parts 1 and 2, pages 599 and 600. Published 1949, by D. Van Nostrand Co., Inc., New York, NY.

General College Chemistry, by J. A. Babor and A. Lehrman, pages 320 and 321. Published 1940 by Thomas Y. Crowell Co., New York, N.Y. 

1. A PROCESS FOR REDUCING THE NICOTINE CONTENT OF DRY TOBACCO IN BULK FORM COMPRISING THE STEPS OF FORCING THERETHROUGH, IN THE ORGER STATED, A CURRENT OF A DRY GAS CONSISTING ESSENTIALLY OF ANHYDROUS HYDROGEN CHLORIDE WITH ADMIXED AIR, A SCAVENGING CURRENT OF AN INERT GAS, AND A CURRENT OF STEAM, SUCH STEPS BEING PERFORMED SEQUENTIALLY. 